The National Security Agency might have listened in on German Chancellor Angela Merkel's cellphone communications, according to the German government. The revelation prompted Merkel to call President Barack Obama for an immediate clarification. Merkel said such an action, if confirmed, would be "a serious breach of trust.”

The White House quickly denied the allegations. "The president assured the chancellor that the United States is not monitoring and will not monitor the communications of the chancellor," White House spokesman Jay Carney said. "The United States greatly values our close cooperation with Germany on a broad range of shared security challenges."

However, Carney did not say whether the U.S. had never monitored Merkel's communications in the past. The German government wouldn't say how it found out about the eavesdropping, but German newspaper Der Spiegel said its research into security files leaked by NSA contractor Edward Snowden had somehow lead to the discovery.

While spying on allies is nothing new, is it different when it extends to the country’s leader? What if tables were turned and the U.S. learned Germany had tapped the cellphone of President Obama? Is it crossing the line to tap into a foreign official's private cellphone calls? Could this harm U.S.-German relations? Should the German government have dealt with this quietly rather than publicly?

Gordon Adams, Professor of U.S. Foreign Policy, American University; Previously under the Clinton Administration, Adams was in charge of the national security budget at the Office of Management and Budget